A human tooth accompanying a hoard of modified shells shaped as tools have been found in the Sakitari-do cave (Nanjo, Okinawa). They are dated to c. 20-23,000 years ago. They seem to be the first known evidence of human presence in the East Asian archipelago.
The Sakitari-do cave is just 1.5 km away from where the Minatogawa human remains were found, which are however of a somewhat more recent date (c. 18-16 Ka ago).
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| Minatogawa 1 (source) |
Source: The Asahi Shimbun (via Pileta).
For what they were... we are 
Millan Mozota
February 17, 2014 at 12:51 pm
The pics of shells are not very promising… I'll wait for an use-wear analysis of the shells. May be they are actually tools, but some extra criteria will probably help to asses it.
Maju
February 17, 2014 at 1:09 pm
I though the same but the presence of a human tooth (and foot bone, forgot to mention) seems to clarify the matter quite a bit, right?
There are two more pics at The Asahi Shimbun article, one with the tooth and the foot bone.
Millan Mozota
February 20, 2014 at 12:49 pm
Yes, of course, but the shells can be food remains, not tools.
Maju
February 20, 2014 at 1:21 pm
I understand that methodical doubt is important in science but, without taking a look at the paper or the materials, I don't think that either of us can doubt their conclusions beyond a vague eyebrow rising. Notice also that two shell fragments appear to have been used as beads.